X ticker is free as Musk weighs a SpaceX-Tesla merger

The US stock ticker X has been unused since Nippon Steel acquired US Steel. Investors speculate Elon Musk could claim the symbol if SpaceX and Tesla merge, though he has not said so.

• Ticker X has been unused since Nippon Steel bought US Steel
• Only five single-letter US tickers are free: I, K, N, X and Y
• Musk called a possible SpaceX-Tesla merger "a good idea"
• SpaceX listed on Nasdaq under the ticker SPCX